Electrical control device



CAPACITY April 4, 1950 M. L. ANTHONY ET AL ELECTRICAL CONTROL DEVICE Filed Jan. 25, 1947 5 b 50 30- a 3 a 30 3/2 5 30 3 g 32' a 52 U U .32

TIME .57 TIME TIME I AMPLIFIER MIXER DISCRIMINATOR H ET RODY N E OSCILLATOR Patented Apr. 4, 1950 UNITED STATES PATENT OFFICE ELECTRICAL CONTROL DEVICE Application January 23, 1947, Serial No. 723,819

Claims. 1

This invention relates to electrical control devices for varying an electrical characteristic.

An object of this invention is to provide an improved electrical control device for varying an electrical characteristic and including a bimetallic sheet which is thermionically heated to varying degrees to obtain the control effect.

In this connection the electrical control device includes an envelope having a cathode and a resilient bimetallic sheet mounted therein. The bimetallic sheet forms an anode to be thermionically heated by the cathode and it has a portion thereof rigidly mounted and the remainder thereof free to flex. When the bimetallic sheet is thermionically heated from'the cathode, the sheet flexes about its mounting as the result of three forces: one, the plate current heats the bimetallic sheet and due to unequal expansion therein the sheet flexes; two, the surface of the bimetallic sheet facing the cathode is heated :by the plate current producing a flexing away from the cathode and which is believed to result from a radiometric effect caused by increased activity of the atmosphere molecules immediately adjacent the heated surface and photoelectronic activity at the heated surface; and three, the surface of the sheet adjacent the cathode is subjected to electron bombardment producing a flexing away from the cathode. The direction of flexing resulting from the first force of course depends upon whether the high expanding or low expanding side of the bimetallic sheet is facing the cathode and the speed of response depends upon the mass of the sheet. The direction of flexing resulting from the second and third forces is always in a direction away from the cathode and the speed of response is substantially instantaneous. These forces may be made to act cumulatively or oppositely to obtain desired results and may be predetermined with respect to each other by predetermining the thickness, mass, type, and position or the bimetallic sheet.

The resilient bimetallic sheet, thus mechanically moved or flexed in accordance with the thermionic heating thereof, cooperates with an electrical control device, such as a condenser, inductance, resistance, or the like for varying an electrical characteristic such as its impedance or reactance in response to the deflections thereof. In the case of the condenser, the resilient bimetallic sheet may form one plate of the con denser.

The amount of thermionic heating of the bimetallic sheet may be readily regulated for example by a control grid in the envelope and a outside. I {I is heated, the ends of the sheet flex inwardly [toward the mica strip l6 due'to the unequal explurality of control devices may, if desired, be controlled by a single control grid.

The fields of application and use of such an electrical control device are widespread but it is found to be'particularly adaptable for use in raw tomatically tuning radio receiving sets.

Further objects of this invention reside in the details of construction of the electrical control device and in the cooperation between the component parts thereof.

Other objects and advantages will become apparent to those skilled in the art upon reference to the accompanying specification, claims, and drawing in which:

Figure 1 is a diagrammatic perspective view of the electrical control device of this invention;

Figures 2, 3, and 4 are graphs illustrating the speed of response of the electrical control device of Fig. 1; and

Figure 5 is a diagrammatic illustration showing the electrical control device of Fig. 1 utilized for automatically tuning a radio receiving set.

Referring first to Fig. 1, the electrical control device is generally designated at it and includes an envelope 9 I in the form of a glass bottle having a pinched end l2 and an evacuating tip 13. Located in the bottle are a pair of spaced electrical control devices and each comprise a ceramic block l4 having a metallic coating l5 on ne surface thereof. The metallic coating preferably is a silver coating. Abutting the metallic coating I5 is a sheet of insulating material it such as mica. A bimetallic sheet I? abuts the mica strip 16 and a portion thereofv is rigidly secured to the ceramic block 14 by suitable securing means such as a rivet E8. The remainder of the bimetallic sheet is permitted to flex. As shown in Fig. 1, the center portion of the bimetallic sheet l! is secured and the ends are free to flex. Also as shown in Fig. 1, the bimetallic sheet i1 is preformed in, arcu'ate shape so that normally the ends of the sheet are spaced fromthe mica strip 16. The low expanding portion ofthe bimetallic sheet is adjacent the mica strip l t and hence the high expanding portion of the sheet is on the Accordingly, when the bimetallic sheet pansion of the elements forming the bimetallic sheet.

The bimetallic sheet I! and the metallic coating I5 on the ceramic block M are electrically insulated from each other by the mica sheet l 6 and form a variable condenser the capacity of which is dependent upon the flexing of the ends of the bimetallicsheet. One element of the condenser,

namely, the metallic coating I5 is electrically connected to a lead 20 extending through the pinched end l2 of the envelope II and the other element of the condenser, namely, the bimetallic sheet I"! is electrically connected to a lead H ex tending through the pinched end l2 oi the envelope ll. Obviously a single variable condenser assembly may be utilized or a plurality of such assemblies may be used and the plurality of the assemblies may have separate electrical leads or the assemblies may be connected in parallel, as illustrated in Figure 1.

Interposed between the condenser assemblies is a cathode 22 electrically connected to a lead 23 extending through the pinched end l2 of the envelope l i. The bimetallic sheets I face the cathode 22 and operate as anodes in conjunction with the cathode 22. The cathode 22 may be of the cylindrical type having a filament therein for heating the cathode. The filament may be electrically connected to leads 24 and 25 also extending through the pinched end I2 of the envelope I I. When the filament is heated to heat the cathode 22, the cathode operates to thermionically heat the bimetallic anodes l1 and the amount of such thermionic heating may be regulated by a control grid 26 interposed between the cathode 22 and the anodes ll. The grid 25 may be electrically connected to a lead 21 extending through the pinched end l2 of the envelope l l. grid voltage is increased, the amount of thermionic heating of the bimetallic anodes I1 is correspondingly increased and, vice versa, .if the grid voltage is decreased, the thermionic heating is correspondingly decreased.

When the bimetallic sheets I? are thermioni cally heated from the cathode 22 under the control of the grid 26, the bimetallic sheets ll flex about their mountings IS and this flexing is caused by three forces: One, The plate current flowing between the bimetallic anodes I! and the cathode 22 heats the bimetallic sheets l1 and due to the unequal expansion in the'bimetallic sheets, the sheets flex and the direction of such flexing is dependent upon the position of the bimetallic sheets. When the high expanding side of the bimetallic sheets are facing the cathode 22, the freeends of the sheets will flex inwardly toward the ceramic block M upon an increase in plate current and they will flex in the opposite direction upon a decrease in plate current. Two, The surfaces of the bimetallic sheets facing the cathode are heated by the plate current and this heating produces a flexing of the free ends of the bimetallic sheets I! away from the cathode 22 and it is believed that this flexing of the free ends results from a radiometric eifect caused by increase molecular activity of the atmosphere molecules immediately adjacent theheated surfaces. Three, The surfaces. of the bimetallic sheets ll facing the cathode 22 are subjected to electron bombardment which also produces a flexing of the free ends of the bimetallic sheets I! away from the cathode.

It is found thatthc flexin of the free ends of the bimetallic elements I! by thesecond and third forces is substantially instantaneous and the amount or such flexing depends upon the amount of thermionic heating. Thus, upon a change in grid voltage, the thermionic heating is substantiall instantaneously changed and the free ends of the bimetallic sheets ll substantially instantaneously flex in response thereto.

The speed of response due to the first force is somewhat slower and movement from. one posi- If the U tion to another of the free ends of the bimetallic sheets due to changes in thermionic heating takes place over an interval of time and, as pointed out above, the direction of such movement depends upon whether the high expanding or low expand ing portions of the bimetallic sheets are facing the cathode. When the high expanding portions of the bimetallic sheets are facing the cathode 22, the three forces are cumulative and operate to flex the free ends of the bimetallic sheets inwardly toward the ceramic block 14 upon an increase inthermionic heating. If, however, the bimetallic sheets H are reversed so that the low exanding portions thereof are facing the cathode 22, then the forces are not cumulative but the first force acts in opposition to the second and third forces. The action of the first force with respect to the second and third forces may be predetermined with respect to each other as by predetermining the thickness and mass of the bimetallic sheets H and the composition of such sheets. For example, if the sheets are made relatively thin, the action due to the second and'third forces may be relatively increased and the action due to the first force may be predetermined by selecting component bimetallic portions having predetermined coefficients of expansion.

Figure 2 is a graph illustrating the speed of response characteristics of the electrical control device of Fig. 1 wherein the high expanding portions of the bimetallic sheets H are facing the cathode 22. The beginning of the curve 30 in Fig. 2 shows the capacity of the variable condenser With a predetermined grid voltage applied. If now the grid voltage is instantaneously increased to a higher value, the thermionic heating instantaneously increases to instantaneously flex the free ends of the bimetallic sheets I toward the ceramic block 14 to instantaneously increase the capacity of the condenser arrangement, and this instantaneously increase in capacit is illustrated in Fig. 2 at 30a. The increased thermionic heating also operates to increase the temperature of the bimetallic sheets and this temperature will increase over a period of time whereby due to the action of the bimetallic sheets, the free ends are flexed further toward the ceramic block M over a time interval to further increase the capacity. Such further increase in capacity over a time interval is designated at 30b. Upon instantaneously decreasing the grid voltage, the reverse action takes place, the capacity instantaneously decreasing as shown at 30c and gradually decreasing as shown at 30d. The relations between 30a and 30b and also between 300 and 30d, as pointed out above, depends upon the thickness and mass and the type of bimetallic sheets utilized.

In Figure 3, the graph 3! illustrates the speed of response of the control device of Fig. l with the bimetallic sheets reversed so that the low expanding portions are facing the cathode. The capacity is illustrated at Fig. l. with a predetermined grid voltage. If now the grid voltage is decreased instantaneously a predetermined amount, the thermionic heating is instantaneously decreased whereby the free ends of the bimetallic sheets flex away from the ceramic block 14 to instantaneously decrease the capacity, as illustrated at Ma. However, the decrease in thermionic heating gradually lowersv the temperature of the bimetallic sheets i! whereby the free ends thereof flex toward the ceramic block [4 to gradually increase the capacity, as illustrated at 311). Upon an increase in grid volt- 5 age, the reverse actions take place as illustrated at3lcand3ld.

By predetermining the thickness, mass, type, and positions of the bimetallic sheets ll, the action due to the second and third forces may be substantially eliminated, as illustrated in Fig. 4, so that the capacity may be gradually varied over a time interval upon changes in grid voltage as illustrated at 32a and 32b. Thus, practically any desired operation of the electrical control device with respect to grid voltage and time may be obtained.

Because the bimetallic element included in the control device provides a time interval or lag in the response, the control is admirably suited for use in automatically tuning a radio receiving set Without danger of the receiving apparatus erroneously tuning to different frequencies.

Figure 5 illustrates the electrical control device I 0 of Fig. l as applied to a radio receiving set for tuning the same. An aerial 35 is suitably connected to an amplifierin box 36 labeled amplifler mixer discriminator oi the radio receiving set which set also includes a heterodyne oscillator 31. The outputs of the amplifier in box 36 and of the heterodyne oscillator 31 are combined in a mixer and a discriminator controlled by the mixer in turn operates to control the control grid 26 of the electrical control device Ill. The variable condenser formed by the metallic coating l5 and the bimetallic sheet l! in the control device in in turn operates to control the heterodyne oscillator 31 to cause the frequency to be the desired frequency. In this way, the electrical control device of this invention may be utilized for automatically tuning radio receiving sets and because of the time lag in the electrical control device, danger of the heterodyne oscillator being tuned to a frequency other than the desired frequency is thereby eliminated.

While for purposes of illustration one form of this invention has been disclosed, other forms thereof may become apparent to those skilled in the art upon reference to this disclosure, and, therefore, this invention is to be limited only by the scope of the appended claims and prior art.

We claim for our invention:

1. An electrical control device comprising an I envelope, an anode in the envelope including a resilient bimetallic sheet having a portion thereof rigidly mounted and the remainder thereof free to flex, a cathode in the envelope for thermionically heating the bimetallic sheet to cause the same to flex about its mounting in proportion to the thermionic heating, means in the envelope cooperating with the bimetallic sheet to form a variable electric impedance device having an impedance varied in proportion to the deflection of the bimetallic sheet, connections across said impedance extending to the exterior of said envelope, and a control grid in the envelope for regulating the amount of thermionic heating.

2. An electrical control device comprising an envelope, a cathode in the envelope, an anode in the envelope including a resilient bimetallic sheet with the low expanding side facing the cathode and having a portion thereof rigidly mounted and the remainder thereof free to flex and adapted to be thermionically heated from the cathode and to be flexed in proportion to the thermionic heating, means in the envelope cooperating with the bimetallic sheet to form a variable electric control device having a reactance varied in proportion to the deflection of the bimetallic strip, and a control grid in the envelope for regulating the amount of thermionic heating.

3. A variable condenser comprising an envelope containing a resilient bimetallic sheet anode having a portion thereof rigidly mounted and the remainder thereof free to flex and forming an anode, a cathode for thermionically heating the bimetallic sheet to cause the same to flex about its mounting in proportion to the thermionic heating, and a rigid conducting sheet in capacitive relationship with the resilient bi- 'metallic sheet, the capacity varying in accordance with the deflection of the bimetallic sheet.

4. A variable condenser comprising an envelope, a resilient bimetallic sheet anode in, the envelope having a portion thereof rigidly mounted and the remainder thereof free to flex, a cathode in the envelope i-or thermionically heating the bimetallic sheet to cause the same to flex about its mounting in proportion to the thermionic heating, a rigid conducting sheet in the envelope cooperating with the resilient bimetallic sheet to form a condenser having a capacity which varies in accordance with the deflection of the bimetallic sheet, and a control grid in the envelope for regulating the amount of thermionic heating.

5. An electrical control device comprising an envelope, a cathode in the envelope, a pair of bimetallic sheet anodes in the envelope on opposite sides of the cathode, each having a portion thereof rigidly mounted and the remainder thereof free to flex, and adapted to be thermionically heated from the cathode and to be flexed 1 in proportion to the thermionic heating, and a rigid conducting sheet in capacitive relationship with each bimetallic sheet anode, the capacity between each rigid sheet and anode varying in accordance with deflection of said anodes.

6. An electrical control device comprising an envelope, a cathode in the envelope, a pair of bimetallic sheet anodes in the envelope on opposite sides of the cathode, each having a portion thereof rigidly mounted and the remainder thereof free to flex, and adapted to be thermionically heated from the cathode and to be flexed in pro-portion to the thermionic heating, a rigid conducting sheet in capacitive relationship with each bimetallic sheet anode, the capacity between each rigid sheet and anode varying in ac-- cordance with deflection of said anodes, and a control grid in the envelope for regulating the amount of thermionic heating.

'7. An electron discharge device comprising an envelope, a cathode in the envelope, a resilient bimetallic sheet anode in the envelope with the high expanding side facing the cathode and having a. portion thereof rigidly mounted, and the remainder thereof free to flex and adapted to be ther-mionically heated from said cathode and to be flexed in proportion to the thermionic heating, a control grid interposed between said cathode and anode to control said thermionic heating and a variable condenser in said envelope, said bimetallic sheet anode being arranged to vary the capacity of said condenser in accordance with the deflection of said sheet anode.

8. An electrical control device including an evacuated envelope, a cathode, a grid, and an anode in said envelope, said anode including a bimetallic sheet having a portion thereof rigidly mounted and the remainder free to flex, and a variable-reactance element-at the side of said anode remote from saidcathode and controlled by the flexure of' said sheet,.there being connections across said reactance element extending to the exterior of said envelope.

9. An electrical control device including an evacuated envelope, a cathode and an anode in said envelope, said anode including a-bimetallic sheet having a portion thereof rigidly mounted and the remainder free to flex, a variable re actance element includingsaid bimetallic sheet and an electrode at the side of said anode remote from said cathode, and connections across said reactance element extending to the exterior of said envelope.

10. An electrical control device including Within an evacuated casing a thermionic discharge system including a source. of electrons, agrid,

and an anode, said anode including a portion 20 of bimetallicmaterial andhaving one part secured and another part free-to flex in accordance with the heating thereof, a variable re 8 actance; element adapted to have its reactance varied by movement of said bimetallic material, and means for making connections across said reactance element from the exterior of said casing.

MYRON L. ANTHONY.

ROBERT M. VIRKUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,605,911 Banneitz Nov. 9, 1926 1,884,591 Davis Oct. 25, 1932 2,454,306 Clifiord et a1 Nov. 23, 1.948

FOREIGN PATENTS Number Country Date 522,965 Great Britain 1- July 2, 1940 520,832 Great Britain May 6, 1940 113,508 Australia July 15, 1941 

